Have you ever been tested for lyme disease. My husband, my son and myself all have the condition. We all have different symptoms at different times. One of the symptoms we suffer with is jaw pain and teeth pain. You can go to my journal pages and see what we have gone through the past year. Lyme disease will make you magnesium deficient. It is worth looking into.
i think the facial pain is separated form the cfs.
trigeminal neuralgia is very much in the same area so is a definite possible. the neurology forum might have answers.
if the neurologist hasn't helped, investigate an osteopath, or acupuncturist, or kinesiologist, or physiotherapist, who if they're good should be able to help with the imbalance. you just have to find a good practitioner. a chiropractor who knows what they're doing should at least have a clue. maxillofacial specialist. some dentists are familiar with tmj too.
sorry if you've already tried all of the above, i know it's annoying when people make dud suggestions! i thought whoever has diagnosed you with tmj should be able to give you more therapeutic relief or rederral on this.
re the pain: the facial pain could be the nerve inflamed. ouch.
the jaw pain i think is from the clench, so is muscular pain and tightness, probably putting pressure on nerves as well.
the clench is from a signal in the brain, trying to balance something up that it thinks is misaligned, but is overdoing it. take care